Process for removing metals from a mineral oil with an alkyl sulfonic acid



United States Patent 3,190,829 PROCESS FOR REMOVING METALS FROM A IAIlIQERAL OIL WITH AN ALKYL SULFONIC D John G. Erdman, Allison Park, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Nov. 29, 1962, Ser. No. 241,042 9 Claims. 7 (Cl. 208-252) This invention. relates to a process for treating mineral oils and more particularly to a process for reducing the heavy metal content especially the porphyrin metallo complex content of mineral oils.

Vanadium, nickel and traces of other metals including iron and copper have been detected in crude oils and in various petroleum distillates, some crude oils containing up to 1000 parts per million, or more, of vanadium. The presence of these metals in catalytic cracking charge stock is undesirbale in that they adversely affect the effective life of cracking catalysts. These metals are undesirable in residual fractions used as fuel because of their tendency to cause corrosion and pitting of materials of construction with which they come in contact. For example, the presence of vanadium in residual fuel oils results in corrosion and fouling of high temperature boilers and the blades and heat exchanger tubes of gas turbines.

A considerable portion of the metals selected from the group consisting of vanadium and nickel when present in mineral oils such as crude petroleum and certain petroleum distillates, exists in the form of stable, non-ionic, oilsoluble complexes. The organic ligands appear to be either porphyrins or the asphaltic molecules contained in the asphaltene and resin fractions. It is believed that only the porphyrin metallo complexes are appreciably volatile and, if entrainment in the distillation process is excluded,

are the only forms in which vanadium and nickel usually occur in distillate oils.

The asphaltic metallo complexes comprise a large group of related compounds, the exact structure of which is not known. In most oils, asphaltic metallo complexes do not make up the entire .asphaltene and resin fractions. The porphyrin metallo complexes can be illustrated by the following structural formula where M is vanadyl (V=O) or nickelous (Ni).

The phsyical and chemical characteristics of the porphyrin metallo complexes coupled with their presence in mineral oils in small amounts, has rendered their removal from oils containing them extremely diflicult.

Porphyrin metallo complexes occur in crude oils obtained from many geographic locations. In preparing distillates from such crude oils a portion of these complexes passes into the products. It has been ascertained that the porphyrin metallo complexes possess sufiicient volatility and thermal stability to distill over with petroleum fractions without decomposition. Regardless of whether the porphyrin metallo complexes are introduced into the distillates by distillation or entrainment their presence is highly undesirable.

Because of their neutral and oil-soluble character, the porphyrin metallo complexes of the type occurring in crude oil, particularly the vanadium complexes, cannot be removed from petroleum stocks by conventional purification procedures. Since the porphyrin metal bonds are usually non-ionic, ion-exchange methods of removal are ineffective. The porphyrin complexes of vanadium and nickel are so stable thermally that their destruction without substantial modification of the oils in which they occur is difiicult. The resinous and aromatic portions of crude oil are adsorbed more readily than the porphyrin metallo complexes on polar adsorbents such as clay thus preventing removal of the complexes in this manner.

Attempts have been made to reduce the porphyrin metallo complexes in catalytic cracking charge stocks by cutting'the crude at temperatures below which the metallo complexes pass into the distillate. While'such attempts to control the porphyrin metallo complexes in the distillates have been at least partially successful, the amount of cracking charge stock obtained from a crude oil is materially reduced. In many instances, desired aromatic fractions in a crude oil have been removed or chemically altered in attempting to remove porphyrin metallo complexes from the oil.

While the asphaltic metallo complexes can be largely removed from crude oils by distillation, porphyrin complexes will pass into the high boiling distillates. Clay adsorption removes the asphaltic metallo complexes along with asphaltic rcsinousand aromatic portions of the oil. If very large amounts of clay are used the porphyrin metallo complexes also are removed. For asphaltic crude oils, this procedure is uneconomic both because of the large amount of clay required andbecause of the loss of a considerable portion of the crude, i.e., the nonmetal containing asphaltic resinous and aromatic port-ions. I have now discovered that a heavy metal constituent including the asphaltic metallo complexes and the porphyrin metallo complexes can be removed from a mineral oil containing the same by contacting the oil containing said heavy metal constituent in the liquid phase at temperature of about 10 to about 250 C. with an alkyl sulfonic acid which is liquid at the treating temperature. In accordance with the invention, the heavy metal constituent is extracted from the oil by the alkyl sulfonic acid without dissolving or chemically altering the aromatic fraction of the oil. The alkyl sulfonic acid, metalfree porphyrins and the heavy metal usually in the form of a heavy metal salt are readily recovered from the extract. The alkyl sulfonic acid, if desired, can be reused for further extractions. The heavy metal, e.g., vanadium and/ or nickel can be recovered from the heavy metal salt. The metal-free porphyrins which are recovered are useful intermediates in the preparation of pigments and dyes, as analytical reagents for the determination of metals, for the refining of low-grade ores and as carriers for metal additives.

Upon contacting an oil containing a heavy metal constituent including asphaltic metallo complexes andporphyrin metallo complexes with an alkyl sulfonic acid according to the process of the invention, two immiscible phases are formed, i.e., an oily (rafiinate) phase and an acid (ext-ract) phase. The raflinate or oily phase comprises an oil of reduced heavy metal con-tent. The extract or acid phase comprises the alkyl sulfon-ic acid, acid-soluble oil constituents including unaltered porphyrin metallo complexes, metal-free porphyrins and heavy metal salts. Separation of the rafiinate from the extract is elfected by any known means such as, for example, by decanting, centrifuging and the like. After separating the raflinate and the extract, the extract upon the addition of a suitable polar liquid miscible with the sulfonic acid but immiscible with the oil such as water, aqueous methanol, dimethyl sulfoxide and the like forms two other phases, i.e., an oily phase and an alkyl .sulfonic acid phase. At this point the heavy metal content may be in the oily phase or in the alkyl sulfonic acid phase depending upon the particular alkyl sulfonic acid and the amount thereof which is used. A routine test can readily determine in which phase the heavy metal content is concentrated. For example, when using methane sulfonic acid at an oil to acid volume ratio of about 2:], the heavy metal content appears almost completely in the alkyl sulfonic acid phase. On the other hand, at an oil to acid volume ratio of about 32:1, the heavy metal content appears almost completely in the oily phase with only a small percentage of metal-free porphyrin and metals appearing in the sulfonic acid phase. The heavy metal which is present in the alkyl sulfonic acid phase is present in the form of an inorganic salt, i.e., vanadium and nickel salts. These salts are removed from the alkyl sulfonic acid by ion exchange or by vacuum distilling the acid. The metal can be recovered from the salt by any known means. Metal-free porphyrins which are present in the alkyl sulfonic acid phase are present essentially in the diacid form and as such are removed from the alkyl sulfonic acid with a suitable solvent such as chloroform. Metal-free porphyrins are obtained from the chloroform extract by neutralization with a material such as ammonium acetate, potassium carbonate and the like. In a preferred embodiment of the invention the recovered alkyl sulfonic acid is recycled to the beginning of the process for further use in reducing the heavy metal content of an oil containing the same.

The alkyl sulf-onic acids which can be employed in the process of the invention are the alkyl mono-, diand poly- .sulfonic acids which are liquid at the temperature used for the extraction and those which are generally considered to be insoluble in mineral oil. The alkyl portion of the acid preferably contains from 1 to 12 carbon atoms. Representative alkyl su-lfonic acids which can be used in the process of the invention thus include methane sulfonic acid, ethane sulfonic acid, propane-2 sulfonic acid, n-butane-2-sulfonic acid, 2-methy'l propane-l-sulfonic acid, n-pentane-Z-sulfonic acid, Z-methyl butane-l-sulfonic acid, n-hexane-Z-sulfonic acid, '2-methyl pentane-Z-sulionic acid, n-octane-Z-sulfonic acid, n-decane-Z-sulfonic acid, n-dodecane-Z-sulfon-ic acid, methane di-sulfonic acid, methane tri-sulf-onic acid, n-octane di-sulfonic acid, n-dodecane tri-sulfonic acid, n-dodecane tetra-sulfonic acid, n-dodecane penta-sulfonic acid and the like. While the alkyl mono su-lfonic acids containing from 1 to 12 carbon atoms can be employed, there is a tendency for the oilsolubility of the alkyl .sulfonic acids to increase as th number of carbon atoms in the alkyl group increases and with the occurrence of chain branching. For this reason, the straight chain lower alkyl sulfonic acids having up to 6 carbon atoms are preferred over the higher homologues thereof. Thus, illustrative examples of the straight chain lower alkyl sulfonic acids in the order of decreasing preference are methane sulfonic acid, ethane sulfonic acid, propane-Z-sulfonic acid, n-butane-Z-sulfonic acid, n-pentane2sulfonic acid and n-hexane-Z-sulfonic acid.

The amount of the alkyl sulf-onic acid employed in the process of the invention is that amount which is at least sufiicient to reduce the heavy metal content including the asphaltic metallo complexes and the porphyrin metallo complexes present in the oil. Generally, amounts ranging from about 0.001 to about 1 volume of acid per volume of oil treated are sufiicient to effect substantially complete removal of the heavy metal content including the asphaltic metallo complexes and the porphyrin metallo complexes from the oil. As noted above, however, as the amount of acid is increased, the heavy metal content in the acid phase also increases.

The present process is generally applicable to all types of mineral oils especially petroleum oils including both petroleum crudes and fractions thereof whether derived from paraffinic, naphthenic or asphalt base stocks which may contain up to 1000 parts per million or more of heavy metals such as vanadium and nickel. Thus, the process can be applied not only to crude petroleum oils and virgin stocks obtained from crude oil distillation units, but also to products obtained from typical hydrocarbon conversi-on processes such as catalytic cracking, hydroforming, steam cracking and coking. While the process of the invention can be applied both to petroleum residual fractions and overhead fractions or distillates, the process of the invention is particularly applicable to petroleum distillates.

In carrying out the process of the invention, the mineral oil charge stock is preferably one which contains little or no water. If the charge stock does contain water, the water is preferably removed from the charge stock before it is treated with the alkyl sulfonic acid. The removal of water is important inasmuch as water dilutes the alkyl sulf-onic acid thus reducing its efficiency and, accordingly, requiring the use of larger amounts of the acid.

In accordance with the process of the present invention, substantial removal of the "heavy metal constituents including the asphaltic metallo complexes and the porphyrin metallo complexes from a petroleum oil containing the same is effected by intimately contacting the oil with the alkyl sulfonic acid at a temperature of about 10 to about 250 C. The particular temperature employed depends to some extent upon the physical properties of the alkyl sulfonic acid and the oil from which the metallo complexes are being removed. In any event, that temperature is employed which insures liquid phase operation. With the lower alkyl sulfonic acids, i.e., C to C alkyl sulfonic acids, room or ambient temperatures are normally used and produce good results.

The treating time depends upon the amount of metal present in the oil, the intimacy of the contacting during the treatment and the temperature at which the treating operaion is conducted. In order to keep the contacting time at a minimum, thorough commingling of the reactants is desirable. I have found that when treating a substantially paraffinic oil containing a relatively small amount of heavy metal constituent as, for example, 20 to 30 parts per million vanadium as porphyrin vanadium complex, a contact time of about thirty minutes is sufiicient at 40 to 50 C. to effect a substantially complete removal of the porphyrin vanadium complex with an acid to oil volumetric ratio of about 0.001 to about 1. Where the oil from which the heavy metal constituent is to be removed is so viscous that intimate contacting with the alkyl sulfonic acid is difficult, it is advantageous to dilute the oil with a suitable hydrocarbon solvent. The solvent should have a boiling point above the contacting temperature at the pressure employed. The volatility of the solvent, however, should be such that it can be readily separated from the oil. When a solvent is used, it can be employed in amounts of about 0.1 to about 5 or more times that of the contaminated oil on a volumetric basis.

The process of the invention can be carried out according to known solvent refining methods including single batch extraction, multiple batch extraction and continuous counter-current extraction. These methods have long been used in the solvent refining of lubricating oils and, therefore, the advantage of one method over another will not be discussed herein.

The process of the invention is illustrated by the following specific examples:

EXAMPLE I Into a 40 ml. round bottom test tube is placed 4.57 grams (approximately 5.0 ml.) of Mara gas oil, boiling to 1135 F., containing 23.9 parts per million total vanadium of which 22.6 parts per million of the metal is present as porphyrin vanadium complexes. The concentration of the porphyrin vanadium complex in the shaken for three minutes as before.

gas oil is 241 parts per million calculated as etioporphyrin I vanadium complex.

The oil is heated to 4050 C. and maintained as closely as possible between these temperature limits throughout the experiment. To the oil is added 2.5 ml. of methane sulfonic acid. The tube is capped and shaken for three minutes. The tube is then centrifuged for about four minutes whereupon the contents of the tube separate into two layers, an oily upper layer designated Raffinate No. 1 and a lower, black acid layer designated Extract No. 1. The raffinate layer is transferred by means of a medicine dropper to another round bottom test tube. The weight of the raflinate is 3.81 grams. To this raflinate (about 4.2 ml.) is added 2.5,ml. of fresh methane sulfonic acid. The tube is capped and Centrifugation for four minutes result in a separation into two phaes, an oily upper layer designated Rafiinate No. 2 and a lower acid layer designated Extract No. 2. Raffinate No. 2 is transferred to another test tube by means of a medicine dropper and washed with a mixture comprising 5 ml. of distilled water and 2.5 ml. of 5 percent aqueous ammonium acetate. The washing procedure consists of shaking the mixture for three minutes followed by centrifugation for four minutes. The washed Raflinate No. 2 Weighs 3.74 grams and represents approximately 82% of the original gas oil. In Rafiinate No. 2, no vanadium is detected by electron spin resonance nor is any vanadium porphyrin complexes detected by visible-ultraviolet spectroscopy. Under the conditions of this experiment, electron spin resonance is capable of detecting at least 1 part per million of total vanadium and the spectral method, 0.23 part per million of vanadium as porphyrin complexes. The treatment with methane sulfonic acid thus substantially completely removes the total vanadium present in the oil.

To Extract No. 1 is added 5 ml. of water and the mixture is shaken for 5 minutes. The mixture is then centrifuged for about 4 minutes whereupon separation into layers occurs, an oily extract layer (1A) and an aqueous sulfonic acid layer. The extract, 1A, is further washed by shaking with a mixture of 5 ml. of water and 2.5 ml. of 5 percent aqueous ammonium acetate. The weight of the oily extract, 1A, is 0.679 g. which represents 14.9% of the original gas oil. Upon examination of the oily extract, 1A, a total vanadium concentration of '33 parts per million is obtained by electron spin resonance which represents 20.5% of the vanadium in the original gas oil. The aqueous sulfonic acid layer has a volume of 7.2 ml. and is red-purple in color. Spectrophotometric examination in the visible region shows that the red color is due to the acid salts of metal-free porphyrins. The metal-free porphyrins essentially in the diacid form are quantitatively extracted from the aqueous acid by extraction with chloroform. After neutralization of the chloroform extract by the addition of a few crystals of ammonium acetate, the metal-free porphyrins are precipitated. The aqueous sulfonic acid layer is nearly colorless.

Extract No. 2 which contains most of the methane sulfonic acid used for the second extraction is diluted with 5 ml. of water, shaken and centrifuged. The oily extract (2A) amounts to only 0.019 g. representing 0.4% of the gas oil. The aqueous sulfonic acid layer is light tan in color indicating only traces of porphyrins. The oily extract (2A) is too small in quantity for determination of vanadium.

The aqueous sulfonic acid fractions are essentially free of petroleum but contain the remaining 80% of the vanadium originally present in the gas oil. The metal is present as vanadyl methyl sulfonate. The sulfonic acid is recovered by first distilling 01f the water and then the sulfonic acid. The vanadium salt remains as a residue. Vanadium is recovered from the metal salt by known electrolytic means.

6 EXAMPLE n Into a round bottom three-necked flask equipped with a stirrer and thermometer is placed 174 g. (200 ml.) of Mara gas oil, boiling to 1135 F., containing 23.9 parts per million of vanadium and 1.5 parts per mill-ion of nickel as determined by wet ashing and colorimetric analysis. Of the vanadium, 226 parts per million is present as porphy-rin complexes. The concentration of the porphyrin vanadium complex in the gas oil is 241 parts per million calculated as etioporphyrin I vanadium complex. The oil is heated to 50 C. and maintained at this temperature throughout the experiment. To the oil is added 147 g. ml.) of methane sulfonic acid. After stirring for 30 minutes, the mixture is centrifuged. Two layers result, i.e., an oily upper layer designated Rafiinate No. 1 and a darker, acidic lower layer designated Extract No. 1. The upper layer is removed by means of a siphon.

After separation, Rafiinate No. 1 Weights 167 g. which contains some methane sulfonic acid. A small aliquot is removed, washed with water, 5% aqueous sodium acetate .and with water until neutral to Congo red test paper. After extraction with pentane and evaporation of the pentane, Ra'fiinate No. 1 represents 65.5% of the gas oil. A large proportionate mechanical loss is encountered at this point because of the small size of the aliquot which is washed. Hence the value of 65.5% would be much larger if no mechanical loss were to occur during washing. In Rafiinate No. l, the total vanadium and nickel as determined by wet washing and colorimetric analysis is 5.4 and 5.7 parts per million, respectively. The value for nickel is high due to experimental error resulting 'from handling extremely small quantities, i.e., in the order of 100 micrograms or less. In Raflinate No. 1, the vanadium present as porphyrin complexes is determined spectrophotometrically to be 08 part per million which corresponds to a reduction of 96.5% in the concentration of porphyrin vanadium complexes.

Extract No. 1 is washed with water, 33% aqueous methane sulfonic .acid, water 5% aqueous sodium acetate, and with water until neutral to Congo red test'p-aper. To remove traces of water, Extract No. 1 is dissolved in methylene chloride and centrifuged. After evaporation of the methylene chloride, Extract No. 1 represents 10.7% of the gas oil. In Extract No. 1 the total vanadium and nick-e1 as determined by wet lashing and colorimetric analysis is 61.9 and 9.6 parts per million, respectively.

The first aqueous wash of Extract No. 1 is a deep purple solution. This solution is filtered and extracted seven times with chloroform to remove nearly all of the purple coloring material. The chloroform solution is neutralized by shaking with solid potassium carbonate. After filtration, the chloroform solution is evaporated to 50 ml. The visible spectrum of 1.00 ml. of this solution diluted to 50 ml. with pyridine shows a four-banded structure typical of neutral porphyrins not complexed with metals. From the spectral curve, it is calculated that based on teioporphyrin I, the chloroform extract contains 30.5 mg. of uncomplexed porphyrins which accounts for 82.6% of the porphyrins originally present in the gas oil. The aqueous solution which has been extracted with chloroform is stored under nitrogen until such time as the vanadium, nickel and methane sulfonic acid can be recovered.

The larger portion of Rafiinate No. 1, 125.7 g., is extracted with an additional 102.8 g. of methane sulfonic acid. After stirring for 30 minutes the mixture is centri fuged. Two layers result, i.e., .an oily upper layer designated Rafiinate No. 2 and a darker, acidic lower layer designated Extract No. 2. The upper layer is removed by means of a siphon.

After separation, R-aflinate No. 2 weighs 109.4 g. This is treated in a manner exactly like Raflinate No. 1. The

final product, Raflinate No. 2, represents 77.5% of the gas oil. In R-aflinate No. 2 the total vanadium and nickel as determined .by wet ashing and colorimetric analysis is 0.2 and 0.4 part per million, respectively, which corresponds to 0.8% and 21% of the vanadium and nickel in the original crude oil. In Raffinate No. 2, the vanadium present .as porphyrin complexes is determined spectrophotometrically to be less than 0.06 part per million 3 71.5% of the orginal gas oil. In Rafiinate No. 2, no vanadium or nickel is detected by the wet ashing or colorimetric method, that is, the concentration of total vanadium is less than 0.1 part per million and total nickel less which corresponds to a reduction of at least 99.7% in the than 0.3 part per million. Thus, at the completion of the concentration of porphyrin to a reduction of at least second extraction with methane sulfonic acid more than 99.7% in the concentration of porphyrin vanadium 99.7% of the total vanadium, and more than 86% of the complexes. total nickel in the original gas oil ha been removed.

Extract No. 2 is treated in a manner exactly like Extrac Spectral examination shows that the ratfinates, while No. 1. The resulting Extract No. 2 represents 2.0% of somewhat lighter in color than the original gas oil, still the original gas oil. In Extract No. 2, the total vanadium contain most of the original aromatic hydrocarbons. and nickel as determined by wet ashing and colorimetric The acidic Extract No. 1 is diluted with 100 ml. of analysis is and 45.9 parts per million, respectively. A water and stirred for minutes. The mixture is then centotal of about 95% of the porphyrins originally present in trifuged whereupon an upper, dark oily layer and a lower the gas oil are recovered as uncomplexed porphyrins from 15 aqueous layer are obtained. On decantation, the oily Extracts No. 1 and 2. layer is subdivided into two fractions, one consisting of a A summary of the data relative to Example 11 are shown dark oil designated Extract 1A and the other consisting i T bl I of a more tarry material designed Extract 1B. Each is Table l Elemental analyses Percent Vanadium (p.p.m.) Fraction of gas S, per- Nickel oil cent by (p.p.m.),

Wt. As total Total porphyrin complexes Original gas oil 100 2. 52 23. 0 22. 6 1. 5 Rallinate No. 1.... 65.5 2. 4s 5. 4 1 0.8 3 5. 7 Extract No. 1 10. 7 4. 88 61.9 1 6.2 9. 0 Rafiinate No. 2 I 77. 5 1. 19 0. 2 0. 06 0. 4 Extract No.2 2. 0 4. 03 15. 0 2 13 45.0

mixed with the complex. proximate.

Under the circumstances, the calculations are necessarily ap- 2 This value is apparently due largely to metal-tree porphyrins: some complexes may be present.

3 This value is high due to experimental error resulting from handling of extremely small quantities, i.e., in the order of 100 micrograms or less.

EXAMPLE III Into a round bottom, three-necked flask equipped with a stirrer and thermometer, is placed 1 kilogram (approximately 1090 ml.) of Mara gas oil, boiling to 1135 F., containing 1.5 parts per million of nickel and 23.9 parts per million of vanadium as determined by wet ashing and colorimetric analysis. Of the vanadium, 22.6 parts per million are present as porphyrin vanadium complex. The concentration of the porphyrin vanadium complex in the gas oil is 241 parts per million calculated as etioporphyrin I vanadium complex. The oil is heated to C. and maintained at this temperature throughout the experiment. To the oil is added 50.4 grams (34.2 ml.) of methane sulfonic acid. After stirring for 30 minutes, the mixture is centrifuged. Two layers results, i.e., an oily upper layer designed Rafi'lnate No. 1 and a lower acidic layer designated Extract No. 1. After separation, Rafiinate No. 1 weighs 860 grams which represents 86% of the gas oil. An aliquot is removed, washed with water, 5% aqueous ammonium acetate and with water until free of ammonium ions. In Raflinate No. 1, the total vanadium and nickel as determined by wet ashing and colorimetric analysis are 1.9 and 0.9 parts per million, respectively, which corresponds to 6.8% and 51% of the vanadium and the nickel in the original gas oil. Thus, the treatment with methane sulufonic acid in a single extraction with an oil to acid volume ratio of about 31 to 1 removes about 93 percent of the total vanadium present and 49 percent of the total nickel present in the gas oil.

The larger portion of Raflinite No. 1, about 745 grams, is extracted with with an additional 50.8 grams of methane sulfonic acid in a manner similar to that above. After separation and washing, Rafiinate No. 2 corresponds to washed with water and a 5 percent aqueous ammonium acetate solution. The final weight of Extracts 1A and 1B is 59.7 g. and g., respectively, corresponding to 6% and 8%, respectively, of the original gas oil. For Extract 1A, the total vanadium and nickel concentrations are 58.6 and 2.4 parts per million, respectively. The vanadium corresponds to 14.7% and the nickel to 9.6% of that in the original gas oil. For Extract 1B, the total vanadium and total nickel values are 193 and 9.8 parts per million, respectively, which corresponds to 65% of the vanadium and 52% of the nickel in the original gas oil. The aqueous sulfonic acid layer is pale red in color. Spectrophotometric examination shows it to contain a very small amount of metal-free porphyrins.

Extract No. 2 is also treated with ml. of water, stirred and centrifuged. After washing with water and 5 percent aqueous ammonium acetate, and water, two fractions are separated by centrifugation. The dark oily layer weighs 63.2 g. which corresponds to 6.3% of the gas oil. Total vanadium and nickel are 15.4 and 0.9 parts per million, respectively, which corresponds to 4.1% of the valnadium and to 3.8% of the nickel in the original gas 01 The aqueous sulfonic acid layers from both extractions are pale red in color. Spectrophotometric examination shows them to contain a small amount of metal-free porphyrin. The sulfonic acid is recovered by first distilling off the water and then the acid. About 18% of the vanadium and 21% of the nickel in the original gas oil are recovered as the sulfonates.

EXAMPLE IV Into a round bottom, three-necked flask equipped with a stirrer and a thermometer, is placed 1 kilogram (approximately 1130 ml.) of Mara crude oil, containing 200 parts per million of vanadium and 16.7 parts per million of nickel as determined by wet ashing and colorimetric analysis. Of the total vanadium present, only 58 parts per million are present as porphyrin complexes. A substantial part of the remainder of the vanadium is present as asphaltic complexes. The concentration of the porphyrin vanadium complex in the crude oil is 618 parts per million calculated as etioporphyrin I vanadium complex. The oil is heated to 50 C. and maintained at this temperature throughout the experiment. To the oil is added 49.89 grams (33.9 ml.) of methane sulfonic acid. After stirring for 30 minutes the mixture is centrifuged. Two layers results, i.e., a fluid upper layer designated Rafiinate No. 1 and a thick, acidic lower layer designated Extract No. 1.

After separation, Raffinate No. 1 weighs 756 grams which represents 76% of the crude oil. An aliquot is removed, washed with 90% methanol-10% water, aqueous sodium acetate, and with water. After centrifugation, Raffinate No. 1 represents 72.1% of the crude oil. In Rafiinate No.- 1 the ttotal vanadium and nickel as determined by wet ashing and colorimetric analysis is 34.8 and 3.4 parts per million, respectively, which corresponds to 12.5% and 14% of the vanadium and nickel in the orginal crude oil. In Raflinate No. 1 the vanadium present as porphyrin complexes is determined spectrophotometrically to be 13.5 parts per million which corresponds to a reduction of 76.7% in the concentration of porphyrin vanadium complexes. The over-all reduction of vanadium, including the asphaltic complexes and the porphyrin complexes, is 165,2 parts per million which corresponds to reduction of 82.6%.

and 7.2% of the vanadium and nickel in the original crude oil. In Rafiinate No. 2 the vanadium present as porphyrin complexes is determined spectrophotometrical ly to be 6.99 parts per million. Thus, at the end of the second extraction, 51.01 parts per million or 87.9% of the vanadium present as porphyrin complexes has been removed. The over-all reduction of vanadium including the asphalt ic complexes and the porphyrin complexes at the end of the second extraction is 181 parts per million or 90.5%.

Extract No. 2 is washed with boiling water, 5% boiling aqueous sodium acetate, and again with boiling water; this procedure is repeated. A portion of the material is stirred with benzene and centrifuged at 16,000 r.p.m. for four hours. The benzene layer is decanted and the benzene removed in a stream of dry nitrogen at 50 C. Some aqueous emulsion remains in the centrifuge tubes. Extract No. 2 represents 7.9% of the crude oil. In Extract No. 2 the total vanadium and nickel as determined by wet ashing and colorimetric analysis is 85.4 and 15.1 parts per million, respectively. The concentration of vanadium as porphyrin complexes is 25.7 parts per million.

A summary of the data relative to Example IV are shown in Table II.

Table II Percent of crude Elemental analyses Vanadium (p.p.n1.) Fraction S, per Nickel Before After In cent 1) (p.p.m.), washing washing washes wt. As total Total porphyrin complexes Crude oil 2 200. 0 58 0 16.7 Rafimate No. 1 75.6 72.1 3.5 l 72 34.8 13 5 3.4 Extract No. 1 24.4 21.7 2.7 4 03 698. 0 134 0 71. 5 Raflilnate No. 2- 65.0 55. 4 9.6 1 72 19. 0 6 99 2. 2 Extract No. 2 10. 6 7. 9 2. 7 2 76 85. 4 7 15.1

Extract No. 1 is washed with boiling water, 5% boil- EXAMPLE V ing aqueous sodium acetate, and again with boiling water. To determine the true dry weight of Extract No. 1, an aliquot of Extract No. 1 is dissolved in methylene chloride. The water which separates is removed. The methylene chloride is then removed and the aliquot is weighed. Extract No. 1 represents 21.7% of the crude oil. In Extract No. 1, the total vanadium and nickel as determined by wet ashing and colorimetric analysis is 698 and 71.5 parts per .million respectively. The concentration of vanadium as porphyrin complexes is 134 parts per million.

The larger portion of Rafiinate No. 1, about 527 grams, is extracted with an additional 26.6 grams of methane sulfonic acid. After stirring for minutes the mixture is allowed to cool and is centrifuged. Two layers result, i.e., a fluid upper layer designated as Raifinate No. 2 and a more viscous lower layer designated Extract No. 2. The layers are separated by siphoning off the upper layer. The distribution between upper and lower layers is made on the basis of resistance between two electrodes at the tip of the siphon tube. The upper layer has a resistance in excess of several megohms while the resistance of the lower layer drops to several hundred thousand ohms.

Into a 15 ml. conical centrifuge tube is placed 1.74

grams (1.90 ml.) of a lighter Mara gas oil, boiling to 1030 F., containing 7.9 parts per million of vanadium as porphyrin vanadium complex. The concentration of the porphyrin vanadium complex in the gas oil is 84 parts per million calculated as etioporphyrin I vanadium complex. Isooctane is added as a solvent for the gas oil to make a total volume of 5 ml. To this mixture is added 2.5 ml. of ethane sulfonic acid. The tube is sealed and shaken for approximately three minutes at C. While maintaining the temperature at about 40 C. the tube is centrifuged for about four minutes whereupon two layers are obtained, i.e., an oily upper layer designated Rafiinate No. 1 and a lower acid layer designated Extract No. 1. After separation, Rafiinate No. 1, consisting of about 4.6 ml. of isooctane-diluted gas oil, is then treated with an additional 2.5 ml. of ethane sulfonic acid at 40 C. with shaking followed by centrifuging as above. Two layers, an upper layer Raffinate No. 2 and a lower layer Extract No. 2 are obtained. The upper layer, Raffinate No. 2, is then washed with 5 ml. of water and 2.5 ml. of 5 percent aqueous ammonium acetate solution at 40 C. to remove any ethane sulill fonic acid. Isooctane is then removed from the washed Raflinate No. 2 by evaporation leaving a solvent-free raffinate corresponding in weight to 86 percent of the original gas oil. Spectral examination or" the solvent-free rallinate shows that porphyrin vanadium complex has been reduced beyond the limit of detection. Under the conditions of the experiment, this value corresponds to less than 0.13 part per million of vanadium. This amounts to a reduction of at least 98 percent of the original vanadium complex in the gas oil. Spectral examination of the raflinate in the ultraviolet region shows that the treatment has not reduced appreciably the concentration of aromatic hydrocarbons. Extract No. 1 and Extract No. 2 are then each separately treated with 5 ml. of water at 40 C. to separately remove and recover aqueous solutions of ethane sulfonic acid. The remaining portions after removal of the aqueous ethane sulfonic acid solution are each washed with a mixture of 5 ml. of water and 2.5 ml. of 5 percent aqueous ammonium acetate to remove ethane sulfonic acid. The residue which remains upon combination consists of 0.2 gram of a black tarry material corresponding to about 12 percent of the original gas oil with a vanadium concentration of 43 parts per million as porphyrin vanadium complex. The concentration of porphyrin vanadium complex in the residue is 459 parts per million calculated as etioporphyrin I vanadium complex. The aqueous ethane sulfonic acid solutions are combined and distilled. Upon distillation of the aqueous ethane sulfonic acid, there are recovered 8.6 ml. of water and 4.5 grams (3.4 ml.) of ethane sulfonic acid which boils at 247 F. at 0.5 mm. of mercury. Since two portions of 2.5 ml. each of ethane sulfonic acid are used in the process, this represents a 68% recovery of the ethane sulfonic acid. The ethane sulfonic acid thus recovered is sufiiciently pure for reuse in removing porphyrin vanadium complexes from an oil containing the same.

The above examples clearly demonstrate the effectiveness of the process of my invention in reducing the heavy metal content including porphyrin metallo complexes from mineral oils and in recovering metal-free porphyrins, heavy metal salts and the alkyl sulfonic acid, if desired, for reuse in the process. Similar results are obtained when the methane and ethane sulfonic acids are replaced by other alkyl sulfonic acids including propane sulfonic acid, n-butane sulfonic acid, n-pentane sulfonic acid, n-hexane sulfonic acid, n-octane sulfonic acid, n-decane sulfonic acid, n-dodecane sulfonic acid, as well as the alkyl diand poly-sulfonic acids such as the C to C alkyl di-, tri, tetraand penta-sulfonic acids.

In addition to obtaining an oil of reduced asphaltic metallo and porphyrin metallo complex content by the process of the invention, there is also evidence in the summary of data for Examples II and IV that some desulfurization of the oil is effected.

While my invention has been described with reference to various specific examples and embodiments it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

I claim:

1. A process for removing a heavy metal constituent from a mineral oil containing the same comprising contacting a mineral oil containing a heavy metal constituent in the liquid phase at a temperature of about to about 250 C. with an alkyl sulfonic acid which is liquid at the treating temperature for a time and in an amount sufiicient to reduce the heavy metal content of the oil and separating a mineral oil of reduced heavy metal content from an alkyl sulfonic acid phase.

2. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate in the liquid phase at a temperature of about 10 to about 250 C. with an alkyl sulfonic acid which is liquid at the treating temperature for a time and in an amount sufiicient to reduce the porphyrin metallo complex content of the distillate and se arating a petroleum distillate of reduced porphyrin metallo complex content from an alkyl sulfonic acid phase.

3. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate in the liquid phase at a temperature of about 10 to about 250 C. with an alkyl sulfonic acid which is liquid at the treating temperature in an amount of about 0.001 to about 1 volume of acid per volume of distillate for a time sutlicient to reduce the porphyrin metallo complex content of the distillate and separating a petroleum distillate of reduced porphyrin metallo complex content from an alkyl sulfonic acid phase.

4. The process of claim 3 wherein the alkyl sulfonic acid is selected from the group consisting of alkyl mono-, diand poly-sulfonic acids containing from 1 to 12 carbon atoms.

5. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate in the liquid phase at a temperature of about 40 to about C. with methane sulfonic acid in an amount of about 0.001 to about 1 volume of acid per volume of distillate for a time suflicient to reduce the porphyrin metallo complex content of the distillate and separating a petroleum distillate of reduced porphyrin metallo complex content from a methane sulfonic acid phase.

6. The process of claim 5 wherein the metal of said porphyrin metallo complex is selected from the group consisting of vanadium and nickel.

7. A process for reducing the porphyrin metallo complex content of a petroleum distillate containing the same comprising contacting said distillate in the liquid phase at a temperature of about 40 to about 50 C. with ethane sulfonic acid in an amount of about 0.001 to about 1 volume of acid per volume of distillate for a time sufiicient to reduce the porphyrin metallo complex content of the distillate and separating a petroleum distillate of reduced porphyrin metallo complex content from an ethane sulfonic acid phase.

8. The process of claim 7 wherein the metal of said porphyrin metallo complex is selected from the group consisting of vanadium and nickel.

9. A process for reducing the metallo complex content of a petroleum crude oil containing the same comprising contacting said crude oil in the liquid phase at a temperature of about 40 to about 50 C. with methane sulfonic acid for a time and in an amount sufiicient to reduce the metallo complex content of the oil and separating an oil of reduced metallo complex content from a methane sulfonic acid phase.

References Cited by the Examiner UNITED STATES PATENTS ALPHONSO D. SULLIVAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,190,829 June 22, 1965 John G. Erdman It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 17, for "phaes" read phases column 6 line 18, for "weights" read weighs line 29, for "washing read ashing same column 6, lines 56 and 57, for "teioporphyrin" read etioporphyrin column 9, line 22, for "ttotal" read total Signed and sealed this 14th day of December 1965.

( L) Attest:

EENEsT w. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A PROCESS FOR REMOVING A HEAVY METAL CONSTITUENT FROM A MINERAL OIL CONTAINING THE SAME COMPRISING CONTACTING A MINERAL OIL CONTAINING A HEAVY METAL CONSTITUENT IN THE LIQUID PHASE AT A TEMPERATURE OF ABOUT 10* TO ABOUT 250*C. WITH AN ALKYL SULFONIC ACID WHICH IS LIQUID AT THE TREATING TEMPERATURE FOR A TIME AND IN AN AMOUNT SUFFICIENT TO REDUCE THE HEAVY METAL CONTENT OF THE OIL AND SEPARATING A MINERAL OIL OF REDUCED HEAVY METAL CONTENT FROM AN ALKYL SULFONIC ACID PHASE. 